Karen catches different sensations, sometimes of sunlight falling upon leaves and bark, other times of cool nighttime air.
All Karen can catch of the music is a melody, plus meaningless syllables. Her guess is that this individual sings, as opposed to humming, but the language is completely meaningless to the tree,
If you'd like Karen to try to figure out the song from the melody, you can roll a relevant dice pool at -4. Since this is a memory/knowledge task, the Gangrel clan weakness applies.
Karen needs also to roll Wits + Empathy.